It's about one-one-hundred-fifty-thousandth the number of Users on Facebook.

In other words, 8,400 is 0.00000583 times the count of Users on Facebook, and the count of Users on Facebook is 172,000 times that amount.

(March, 2015 figures) (monthly active users)
Facebook had 1.44 billion active users for the month ending March, 2015. In August, 2014, Facebook began a process of removing 87 million accounts that it had found to be fake.

It's about one-seven-thousand-five-hundredth the number of Copies of Michael Jackson's Thriller Sold (2011).

In other words, the count of Copies of Michael Jackson's Thriller Sold (2011) is 7,700 times 8,400.

(sales figures as of 1990) (1982 release)
Michael Jackson's Thriller, the best-selling album of all time, has sold over 66 million copies since its release. Following its release in 1982, the album â€” which contains hits like "Thriller," "Beat It," and "Billie Jean" â€” won eight (8) Grammy Awards in 1984.